The ultimate aim of this research is to achieve the cryopreservation human organs and vascularized tissues. To attain this goal it will be necessary to achieve low stabilizing temperatures without the formation of ice (vitrification). We have shown that this can be done using cryoprotective solutes at high concentration in combination with hydrostatic pressure. The formation of ice during warming of vitrified solution (devitrification) is a major obstacle and this phenomenon and its relationship to the composition of vitrification solutions, to pressure and to temperature will be analyzed. Rapid warming is essential to avoiding or minimizing devitrification. Small specimens have been successfully vitrified and rewarmed but scaling the procedure up to handle large mammal organs will require electromagnetic heating at high energy levels. The in the tolerated cryoprotectant toxicity will be studied in hope of achieving an increase in the tolerated cryoprotectant concentration which would moderate the need for pressure high rates of rewarming. The perfusion and vitrification organs will focus initially on rabbit kidneys, progressing to pig and human kidneys, with function assayed by short term allograft or permanent autograft transplantation.